Regarding pdf digital signature green tick

Hi,

   I am using iTextpdf library for adding digital signature to the pdf file and verifying the Digital signature in adobe pdf reader. In adobe reader it is showing signature is valid, but green tick is not showing, i need the green tick behind the signature. i tried adding trust certificates in my adobe reader but nothing changed. Can anybody suggest how we can add green tick to digital signature (green tick is must for my project) and provide some information regarding whether green tick is required compulsory or not. And if i send the digitally signed pdf to other to check how they can verify the digital signature.

Thank you,

Manjunath